Basic and clinical investigation of the mechanisms underlying hearing are being conducted by a multidisciplinary consortium of workers from the Massachusetts Institute of Technology, the Harvard Medical School, the Massachusetts General Hospital and the Massachusetts Eye and Ear Infirmary. The research focuses on normal and pathological physiol gy of the vertebrate auditory system. Studies of middle and inner ear mechanics, sensory transduction, auditory-nerve activity and central nervous system organization are based on anatomical and physiological data from lizards, cats and humans. Clinical studies on patients with hearing disorders of various origins are aimed at improving diagnostic capabilities and suggesting new forms of treatment.